Note: Descriptions are shown in the official language in which they were submitted.
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AIRCRAFT OCCUPANT PROTECTION SYSTEM
Technical Field
The present disclosure relates generally to aircraft safety systems, including
safety systems that comprise crash attenuation systems for aircraft.
Description of the Prior Art
Currently internal airbags are used in the automotive industry within the
occupied volume to mitigate occupant injuries. Similarly, external airbags
have been
used to attenuate decelerative loads to air and space vehicles, such as escape
modules, upon contact with the ground or water. Examples include the NASA Mars
Rovers and the crew module of the General Dynamics/Grumman F-111.
During impact, the gas in the airbag must be vented to prevent gas
pressurization and subsequent re-expansion, which may cause the occupant to
accelerate backward. This effect is commonly known as rebound. In addition,
the
gas may be vented to prevent over-pressurization, which can cause failure of
the
airbag. Venting may be accomplished, for example, through discrete vents or
through a porous membrane that forms at least a portion of the skin of the
airbag.
One shortcoming of prior external airbag systems is that they fail to prevent
post-impact pitch-over, or "tumbling," of an aircraft having a forward and/or
lateral
velocity at impact with a hard surface. For example, referring to Figures 1a-
1e, an
aircraft 10 that is equipped with a prior external airbag system 12 is shown
at
different points during a crash sequence from (a) to (e). The crash sequence
involves the aircraft 10 having both forward and downward velocities at (a)
and (b).
The airbag system 12 properly deploys its airbags 14 at (b), but still incurs
serious
damage due to pitch-over of the aircraft 10 as shown at (d) and (e). Thus,
improvements are still needed in external airbag systems, particularly
improvements
to the pitch-over stability of an aircraft equipped with an external airbag
system.
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Brief Description of the Drawings
For a more complete understanding of the present disclosure, including its
features and advantages, reference is now made to the detailed description
taken in
conjunction with the accompanying drawings, in which:
Figures la-le show a crash sequence for a helicopter equipped with a prior
external airbag system;
Figure 2 is a perspective view of a helicopter equipped with an external
airbag
system;
Figure 3 is a perspective view of an airbag used with the external airbag
system shown in Figure 2;
Figures 4a-4c are cross-sectional views of a vent valve in full-open,
partially-
open, and closed configurations, respectively;
Figure 5 is a diagram of the vent plate shown in Figures 4a-4c;
Figure 6 is block diagram of the helicopter shown in Figure 2;
Figure 7 is a block diagram illustrating the operation of the crash
attenuation
system of the helicopter shown in Figure 2;
Figure 8 shows a chart of exemplary data representative of a relationship
between airspeed of the helicopter and open vent area;
Figures 9a-9d show a crash sequence for a helicopter equipped with an
external airbag system according to the present disclosure;
Figure 10 shows a cross-sectional view of an airbag of the external airbag
system of the present disclosure;
Figure 11 shows a perspective view of a helicopter equipped with an
alternative external airbag system;
Figure 12 shows a block diagram of an occupant protection system;
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Figure 13 shows a block diagram of a more detailed embodiment of the
occupant protection system shown in Figure 12;
Figure 14 shows a partial top view of a venting system for a crash attenuation
system;
Figure 15 shows a partially sectioned side view of a first embodiment of the
venting system shown in Figure 14;
Figure 16 shows a partially sectioned side view of a second embodiment of
the venting system shown in Figure 14;
Figure 17 shows a cross-sectional side view of the vent passage of the
venting system shown in Figure 14, illustrating a first embodiment of a vent
valve for
the venting system; and
Figure 18 shows a cross-sectional side view of the vent passage of the
venting system shown in Figure 14, illustrating a second embodiment of a vent
valve
for the venting system.
Description of the Preferred Embodiment
The present disclosure provides for a number of safety improvements for
aircraft, including an impact detection system, an impending crash detection
system,
and an inflatable crash attenuation system for an aircraft.
The inflatable crash attenuation system can comprise an airbag that is
inflated
prior to impact and controllably vented during impact so as to prevent
aircraft pitch-
over. The system can be used on a number of different types of aircraft, for
example, helicopter, fixed wing aircraft, and other aircraft, and in
particular those that
are rotorcraft. The system improves on the prior art by providing automatic
control of
the venting valves based on sensed crash conditions, thereby effectively
shifting the
center of impact pressure and preventing aircraft pitch-over.
Figure 2 shows a helicopter 100 incorporating the crash attenuation system
according to the present disclosure. Helicopter 100 comprises a fuselage 102
and a
tail boom 104. A rotor 106 provides lift and propulsive forces for flight of
helicopter
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100. A pilot sits in a cockpit 108 in a forward portion of fuselage 102, and a
landing
skid 110 extends from a lower portion of fuselage 102 for supporting
helicopter 100
on a rigid surface, such as the ground.
A problem with rotor 106 or the drive system for rotor 106 may necessitate a
descent from altitude at a higher rate of speed than is desirable. If the rate
is an
excessively high value at impact with the ground or water, the occupants of
helicopter 100 may be injured and helicopter 100 may be severely damaged by
the
decelerative forces exerted on helicopter 100. To reduce these forces, an
airbag
assembly 111 comprising inflatable, non-porous airbags 112, 114 is installed
under
fuselage 102. Though not shown in the drawings, airbags 112, 114 are stored in
an
uninflated condition and are inflated under the control of a crash attenuation
control
system (described below).
Figure 3 is an enlarged view of airbag 112, which has a non-porous bladder
116, which is sealed to a housing 117 having a plurality of discrete vents
118.
Airbag 112 is shown in Figure 3, but it should be noted that airbags 112 and
114 can
have generally identical configurations. In a preferred embodiment, the
bladder 116
is formed of a fabric that comprises resilient material such as Kevlar and/or
Vectran.
Vents 118 communicate with the interior of bladder 116, allowing for gas to
controllably escape from within the airbag 112. In the embodiment shown, vents
118
are open to the ambient air, though vents 118 may be connected to a closed
volume,
such as another airbag or an accumulator (not shown). Also, while a plurality
of
vents are shown in the embodiment illustrated in Figure 3, alternative
embodiments
can include only a single vent 118.
Referring to Figures 4a-4c, each vent 118 has a vent valve 120 for controlling
the flow of gas through vent 118. Vent 118 and vent valve 120 together form a
vent
passage 122 for channeling gas flowing out of airbag 112. Each vent valve 120
is
sealingly mounted in housing 117 (or bladder 116 in some embodiments) to
prevent
the leakage of gas around vent 118, which forces venting gas to flow through
passage 122. A vent plate 124 is configured to be moveable between an open
position, for example shown in Figure 4a, at least one intermediate position,
for
example as shown in Figure 4b, and a closed position, for example as shown in
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Figure 4c. Figure 4a shows vent plate 124 in the open position, or open state,
in
which a maximum amount of gas is allowed to flow through passage 122 from
within
airbag 112. Figure 4b shows vent plate 124 in an intermediate position, or
intermediate state, in which a selected amount of gas less than the maximum is
5 allowed to flow through passage 122 from within airbag 112. Figure 4c shows
vent
plate 123 in the closed position, or closed state, in which gas is prevented
from
flowing out of airbag 112 through the passage 122. Though only a single
intermediate position is shown, it should be understood that various
additional
intermediate positions can be selected in order to control the amount of gas
that is
allowed to escape from within the airbag 112 through the vent 118. Also, while
the
vent valve 120 is shown as a sliding valve, it will be understood by one
skilled in the
art that vent valve 120 may alternatively be other suitable types of valves.
Control of
vent valves 120 may be accomplished though any number of means, including, for
example, electrorheological means. In some embodiments, the vents 118 can be
sealed with an optional pop-off pressure release mechanism, preferably a
pressure
sensitive fabric 125. In such embodiments, once the fabric 125 pops off, the
vent
valve 120 controls release of the pressurized air inside the airbag 112, 114.
Referring next to Figure 5, as will be discussed in greater detail below, each
vent plate 124 can be selectively positioned to any position between a full
open
position and a full closed position. In the view shown in Figure 5, the
hatched area
127 represents the open vent area, through which gas can escape from within an
airbag 112 or 114 through passage 122. The vent plate can be moved a distance
A
according to a desired amount of open vent area 127. The open vent area 127
will
be a total open vent area "S" if there is only one vent 118; otherwise, the
open vent
area 127 of each vent 118 is summed to be a total vent area "S." The total
vent area
S is a function of crash conditions:
S = f (.i,,61,0, d, 0, A, ===)
where .i represents forward velocity, 2 represents downward or sink velocity,
0
represents pitch angle, 0 represents roll angle, 6 represents pitch rate, 0
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represents roll rate, and A represents the slope of the impact surface (e.g.,
the slope
of the ground).
Figure 6 shows airbags 112 and 114 mounted to a lower portion of fuselage
102 and show additional components of the crash attenuation system according
to
the present disclosure. A computer-based control system 126, which is shown
mounted within fuselage 102, is provided for controlling the operation of
components
associated with airbags 112, 114. Each airbag 112, 114 has a gas source 128,
such
as a gas generator, for inflation of the airbags 112, 114. In some
embodiments, a
secondary gas source, such as compressed gas tank (not shown), can be provided
for post-crash re-inflation of airbags 112, 114 so that the airbags 112, 114
can be
used as floatation devices in the event of a water landing. The gas source 128
may
be of various types, such as gas-generating chemical devices or compressed
air, for
providing gas for inflating airbags 112, 114. In addition, the crash
attenuation
system has a sensor system 130 for detecting crash conditions used to
determine
the total vent area S, such as rate of descent and/or ground proximity.
Airbags 112,
114 can also have a water-detection system (not shown), which may have sensors
mounted on fuselage 102 for detecting a crash in water. Gas source 128, vent
valves 120, and sensor system 130 are in communication with control system
126,
allowing control system 126 to communicate with, monitor, and control the
operation
of these attached components. In
addition, control system 126 may be in
communication with a flight computer or other system for allowing the pilot to
control
operation of the crash attenuation system. For example, the pilot may be
provided
means to override, disarm, or arm the crash attenuation system.
The sensor system 130 is shown in Figure 6 as a discrete component for the
sake of convenience. However, it should be noted that actual implementations
of the
sensor system 130 can comprise a number of components that are located at
various locations on the helicopter 100. The sensor system 130 can include,
for
example, sensors for detecting pitch and roll attitude, pitch and roll rate,
airspeed,
altitude, rate of descent, and slope of the impact surface.
Referring next to Figure 7, an exemplary embodiment of the sensor system
130 is configured to detect various crash conditions, which can include, for
example,
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one or more of the sink speed, forward speed, pitch and roll attitude, pitch
and roll
rate, and proximity to the ground of the helicopter 100. The control system
126
receives data from the sensor system 130 representative of the detected crash
conditions. In a preferred embodiment, the control system 126 is a
microprocessor-
based system configured to operate as a crash predictor. When excessive
oncoming velocity of the ground within a certain altitude range is detected by
the
control system 126, the gas source 128 is triggered to inflate the airbags
112, 114
(indicated at box 126A) prior to impact of the helicopter 100 with the ground.
At the
same time, the control system 126 activates the vent valves 120 to adjust the
open
vent area based on an active vent valve algorithm as indicated at box 126B.
Figure 8 shows an example of a relationship that can be used by the control
system 126 for adjusting the open vent areas at 126B. In Figure 8, a chart is
shown
that illustrates a relationship between open vent area and forward velocity of
a
helicopter for a given sink velocity of 36 feet per second. The line 134 maps
open
vent areas to forward velocities for the forward airbag 112, while the line
136 maps
open vent areas to forward velocities for the aft airbag 114. It should be
appreciated
that the relationship will vary for different sink velocities. The
relationship will also
vary depending on a number of other factors, for example aircraft
characteristics,
such as aircraft weight and balance, and the number and characteristics of the
airbags. The data can be determined using known flight simulation techniques,
for
example simulation software, for simulating crash results. Using such
techniques,
data can be collected based on simulation of crash results for various crash
conditions and open vent areas.
Figures 9a through 9d illustrate operation of the crash attenuation system. In
operation, if an impending crash is sensed by sensor system 130, for example,
by
excessive oncoming rate of the ground within a certain attitude range, control
system
126 triggers gas source 128 to inflate airbags 112, 114 at the appropriate
time to
allow inflation just as airbags 112, 114 contact the impact surface (ground or
water).
Figure 9a shows an impending crash onto ground 132, which is sensed by the
control system 126 based on data received from the sensor system 130. At
Figure
9b, gas source 128 is triggered, causing airbags 112 and 114 to inflate just
prior to
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contact with ground 132. The control system 126 also calculates the open vent
areas for each of the airbags 112, 114. In this case, the control system 126
determines that the crash conditions correspond to the line 138 shown in
Figure 8,
which requires the open vent area of aft airbag 114 be greater than the open
vent
area of forward airbag 112. Accordingly, at Figure 9c the open vent area of
aft
airbag 114 is set to an area of about 0.0205 square meters and the open vent
area
of forward airbag 112 is set to an area of about 0.0145 square meters. Thus,
as
shown in Figure 9c, the aft airbag 114 deflates faster than the forward airbag
112.
As a result, as shown at Figure 9d, the helicopter 100 comes to a stop without
experiencing a pitch-over.
Referring next to Figure 10, a cross-section of a preferred embodiment of an
airbag 112, 114 is shown. The hatched area 140 represents the portion of the
airbag
112, 114 that is adjacent to the underside of the fuselage 102. The arrow 142
points
towards the forward end of the helicopter 100. The broken line 144 is the
widest
portion of the airbag 112, 114 between the top (hatched area 140) and bottom
146 of
the airbag 112, 114. As shown in Figure 10, for a width W of the airbag at
line 144,
the distance D1, which is the distance between the top 140 and the line 144,
and the
distance D2, which is the distance between the bottom 146 and the line 144,
are
equal and determined based on the following relationship:
W
D1, D2 =
21/3
This geometry maximizes crush distance for optimal energy absorption
management. Also, the curved region 148 provides anti-plow, anti-scooping
geometry to assist in preventing pitch-over of the helicopter 100.
Referring next to Figure 11, an alternative embodiment of the helicopter 200
is
shown. As mentioned above, while the present crash attenuation system has been
discussed primarily in connection with two airbags 112, 114, alternative
embodiments can have additional airbags. For example, the helicopter 200 shown
in
Figure 11 has an airbag assembly 211 comprising four airbags 212, 213, 214,
and
215. Like the helicopter 100, the helicopter 200 comprises a fuselage 202 and
a tail
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boom 204. A rotor 206 provides lift and propulsive forces for flight of
helicopter 200.
A pilot sits in a cockpit 208 in a forward portion of fuselage 202, and a
landing skid
210 extends from a lower portion of fuselage 202 for supporting helicopter 200
on a
rigid surface, such as the ground.
A problem with rotor 206 or the drive system for rotor 206 may necessitate a
descent from altitude at a higher rate of speed than is desirable. If the rate
is an
excessively high value at impact with the ground or water, the occupants of
helicopter 200 may be injured and helicopter 200 may be severely damaged by
the
decelerative forces exerted on helicopter 200. To reduce these forces,
inflatable,
non-porous airbags 212, 213, 214, and 215 are installed under fuselage 202.
Though not shown in the drawings, airbags 212, 213, 214, and 215 are stored in
an
uninflated condition and are inflated under the control of a crash attenuation
control
system.
The crash attenuation system of the helicopter 200 can operate as discussed
above in connection with the helicopter 100. In addition, compared to the
helicopter
100, the helicopter 200 provides additional lateral roll-over prevention
capabilities.
Each of the airbags 212, 213, 214, and 215 is independently actively vented
during a
crash sequence. Thus, if the helicopter 200 is approaching the ground with a
lateral
velocity, the airbags 212 and 214, which are located along one side of the
helicopter
200, can be vented more or less than the airbags 213 and 215, which are
located
along the other side of the helicopter 200, as necessary based on detected
crash
conditions in order to prevent the helicopter 200 from rolling over after
impact with
the ground.
The above disclosure describes a system and method for actively controlling
the venting of external airbags based on sensed crash conditions, such as
airspeed,
sink speed, pitch attitude, roll attitude, pitch rate, and roll rate. This
active venting of
the external airbags causes different airbags located at different locations
of an
aircraft exterior to deflate at different rates upon impact, thereby shifting
an aircraft's
center of impact pressure.
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Turning next to Figure 12, a block diagram shows an occupant protection
system (OPS) 300. The OPS 300 provides a control system that computes various
impact scenarios (forward/vertical velocities, pitch/roll attitudes,
pitch/roll velocities,
impact angle, and likely surface characteristics) based upon signals detected
by
5 various sensors 302, electronic maps, and other available data. The control
system
algorithm is then used to actively control and schedule various safety systems
throughout the aircraft. The OPS 300 includes a sensor system 302, which can
serve
as an embodiment of the sensor system 130 described above. The OPS 300 also
includes an impact detection system 304 and an impending crash detection
system
10 306, either one or both of which can serve as the control system 126
described
above. The impending crash detection system 306 is configured for detecting an
imminent crash, while the impact detection system 304 is configured for
detecting
the actual occurrence of a crash.
The impending crash detection system 306 is in communication with one or
more sensors of the sensor system 302. While the aircraft is in flight, the
impending
crash detection system 306 can be configured for periodically receiving
information
from one or more sensors of sensor system 302 as well as other available data
from
other aircraft systems. The crash detection system 306 is configured to
evaluate the
received information and determine whether there is excessive oncoming
velocity of
the ground within a certain altitude range, as would occur in the event of an
imminent
impact. If an impending crash is detected, the crash detection system 306 is
configured to communicate with one or more impending crash safety systems 310
in
order to initiate a series of actions to protect the occupants of the
aircraft.
The impact detection system 304 is configured for detecting whether an actual
impact is occurring or has occurred. While the aircraft is in flight, the
impact
detection system 304 can be configured for periodically receiving information
from
one or more sensors of sensor system 302 as well as other available data from
other
aircraft systems. The impact detection system 304 is configured to evaluate
the
received information and determine whether an impact is occurring or has
occurred,
for example by detecting a sudden stop or drop in forward and/or downward
velocity
as would occur during an impact. If an impact is detected, the impact
detection
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system 304 is configured to communicate with one or more impact safety systems
308 in order to initiate a series of actions to protect the occupants of the
aircraft.
Turning next to Figure 13, a more detailed block diagram shows an example
of an embodiment of the OPS 300. In the illustrated embodiment, the sensor
system
302 includes one or more of the following: one or more accelerometers 312, a
Global
Positioning System (GPS) and/or Inertial Navigation System (INS) 314, a
Helicopter
Terrain Awareness Warning System (HTAWS) and/or Enhanced Ground Proximity
Warning System (EGPWS) 316, an altimeter 318, and a Transponder Collision
Avoidance System (TCAS) 320.
Impact detection system 304 includes impact detection logic 304a, which
receives and evaluates data from one or more accelerometers 312. Data from the
accelerometers 312 can be evaluated by the impact detection system 304 in
order to
determine whether an impact is occurring or has occurred. If an actual impact
is
detected, the impact detection system 304 can control one or more of the
impact
safety systems 308 to take one or more predetermined actions that would be
desirable in the event of a crash. Figure 13 shows the following examples of
impact
safety systems 308: internal airbags 322, collapsible cyclic stick 324, soft
pedals
326, fuel shutoff valves 328, fuel ventilation 330, fire extinguishers 332,
egress
lighting 334, door latches 336, and an Emergency Locator Transmitter (ELT)
338.
The impact safety systems 308 can include conventional systems or systems
that improve on conventional systems. For example, the internal airbags 322
can be
of the type known in the art for use in aircraft and automobiles in order to
help
prevent injuries during a crash.
A collapsible cyclic stick is disclosed in U.S. Patent No. 5,431,361 to
Carnell
et al.. The collapsible cyclic stick disclosed by Carnell et al. is designed
for use in
combination with an energy attenuating stroking crew seat. The Carnell et al.
cyclic
stick is mechanically connected to the seat such that the cyclic stick is
displaced as a
result of the stroking action of the seat during a severe crash. The
collapsible cyclic
stick 324 can be similar to the Carnell cyclic stick, except that an actuator
or the like
is used to
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displace or collapse the collapsible cyclic stick 324 according to control
signals from
the impact detection system 304. Similarly, the soft pedals 326 are
controllable by
the impact detection system 304 to collapse, displace, or become freely
movable if
an impact is detected. These measures help prevent injury to the pilot during
a
crash that could otherwise occur due to forceful contact with the cyclic stick
and/or
pedals.
A number of systems are controlled in order to reduce the risk of fire during
and after an impact. For example, the fuel shutoff valves 328 can be
controlled to
close and/or the fuel pump can be shut off, for example via a Full Authority
Digital
Engine Control (FADEC) if the aircraft is so equipped. Similarly, fuel
ventilation 330
can be closed in order to prevent the release of flammable vapors into a crash
environment that might include ignition sources, such as sparking from damaged
wiring. Also, fire extinguishers 332 can be armed and/or activated.
Other systems can be controlled for making it easier for the pilots and crew
to
exit the aircraft, such as activation of egress lighting 334, unlocking and/or
opening
door latches 336. An active rotor brake can stop the rotating blades overhead
to
protect the occupant's heads. An automatic seatbelt release would speed egress
in
the event of a water landing and the aircraft filling with water. Finally, an
Emergency
Locator Transmitter (ELT) 338 can be activated for allowing the aircraft to be
located
by search parties.
In addition, the impact detection system 304 can issue an impact detection
signal to a float control 340. The float control 340 also receives data from
an
immersion sensor 342 and from a terrain database 344. Based on the received
data, the float control 340 can be configured to activate external airbags
and/or life
rafts 346 in the event of a water landing or crash. Floats would be configured
to
preserve the breathable airspace within the aircraft in case the aircraft
rolls or flips
over.
These and other systems can be activated by the impact detection system
304 since they are desirable in the event of an actual crash, but should not
be
activated unless an actual crash has occurred because they would hinder the
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operation of the aircraft. Other systems designated as impending crash safety
systems 310 can be controlled for improving safety during impact, but do not
hinder
operation of the aircraft so they can be activated earlier than the impact
safety
systems 308 before an actual crash has occurred.
Impending crash detection system 306 includes impending crash detection
logic 306a, which receives and evaluates data from sensor systems 302, which
can
include one or more accelerometers 312, GPS and/or INS 314, HTAWS and/or
EPGWS 316, radar altimeter 318, and TCAS 320. The impending crash detection
system 306 also receives airspeed data from air data computer (ADC) 360 via a
sea
state, wind vector estimator 362. Data from the sensor system 302 can be
evaluated
by the impending crash detection system 306 in order to determine whether an
impact is likely to occur. If an impending crash is detected, the impending
crash
detection system 306 can control one or more of the impending crash safety
systems
310 to take one or more predetermined actions that would be desirable in the
event
of an impending crash. Figure 13 shows the following examples of impending
crash
safety systems 310: automatic flare system 348, active restraint system 350,
active
seat control system 352, as well as a crash attenuation system, which can be a
crash attenuation system according to any of the embodiments disclosed herein,
having an active vent controller 354 and external airbags 356.
The impact safety systems 308 can include conventional systems or systems
that improve on conventional systems. For example, the automatic flare system
348
can be of the type of maneuver known for decelerating the helicopter in order
to
reduce forward speed and decrease the rate of descent. The impending crash
detection system 306 can also send data to a crash heading command controller
364, which can determine a vehicle state (velocities, rates, accelerations,
etc) and
make adjustments to the flight control system 366. The active restraint system
350
can include an haul-back restraint system where shoulder restraints are
retracted in
order to straighten the spine of the pilot or crewmember. This helps to
properly
position the person for impact in order to reduce the chances of a back or
neck injury
to the extent possible. The active seat control system 352 can be activated to
control seats to stroke downwardly during a crash in order to absorb some of
the
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force of impact. The impending crash detection system 306 can also activate an
active landing gear controller 370 to extend and stiffen landing gear 372 for
maximum energy absorption.
Turning now to Figures 14-21, various embodiments of venting systems for
the crash attenuation systems disclosed herein will be described. While the
venting
system is described below in connection with a single airbag, it should be
appreciated that multiple venting systems can be used with multiple airbags on
a
single aircraft. For example, the venting systems shown in Figures 14-21 can
be
used with a two-airbag crash attenuation system such as the one shown in
Figure 2,
and can also be used with a four-airbag crash attenuation system such as the
one
shown in Figure 11.
Figure 14 shows a partial top view of a venting system 400 for a crash
attenuation system comprising an airbag 402 (partially shown in Figure 14) and
a
housing 404. The venting system 400 would ordinarily be disposed on the
underside
of an aircraft; however, no aircraft is shown in Figure 14 in order to allow
for an
unobstructed view of the venting system 400. The airbag 402 can be identical
to
airbags 112 and 114, and the housing 404 can be identical to the housing 117.
The
venting system 400 is configured for controlling whether gas is allowed to
escape
from within the airbag 402 and housing 404. The venting system 400 can be
controlled by a control system such as control system 126 or controller 354 as
described above. Figure 14 also shows an inflator 406 that is controllable by
a
control system, such as control system 126 or controller 354, for inflating
the airbag
402.
The venting system 400 includes a vent passage 408. The vent passage 408
is formed by rigid substrates, for example formed of sheet metal or another
rigid
material. The vent passage 408 extends between a first opening 410 within the
housing 404, and a second opening 412 external to the airbag 402 and housing
404.
One or more vent valves 414 are disposed within the vent passage 408. The vent
valves 414 can include active valves that are controllable for regulating the
flow of air
through the vent passage 408 as described above in connection with vent 118.
The
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vent valves 414 can also include pop-off valves that are designed to burst
under the
force of a predetermined amount of air pressure.
Turning next to Figure 15, a partially-sectioned side view is shown of venting
system 400, as well as airbag 402 and housing 404 all supported by an aircraft
5 fuselage 416. In this embodiment, the upper side of the vent passage 408 is
flush
with the under side of the fuselage 416. In Figure 15, the airbag 402 is
inflated and
supporting at least a portion of the fuselage 416. In this situation, the
airbag 402 is
compressed by the weight of the aircraft and the upper portion of the airbag
402 is
pressed against the under side of the fuselage 416 and the vent passage 408.
The
10 vent passage 408 is at least long enough to extend beyond the upper portion
of the
airbag 402. Otherwise, the upper portion of the airbag 402 would form a seal
that
could prevent air from escaping from within the airbag 402.
In Figure 15, the vent passage includes a vent valve 414 that can be
controlled to move to any position between the fully open position shown in
solid
15 lines and the fully closed position shown in broken lines. As discussed
above in
connection with vent 118 and vent valve 120, various intermediate positions of
the
vent valve 414 between the fully opened and fully closed positions can be
selected in
order to control the amount of gas that is allowed to escape from within the
airbag
402 through the vent passage 408. While the vent valve 414 is fully or
partially
opened, air can escape from within the airbag 402 through the vent passage as
indicated by arrows 418-420. While the vent valve 414 is fully closed, the
vent
passage 408 is sealed by the vent valve 414 so that air cannot escape through
the
vent passage 408. Also, in the event of a water landing, the vent valve 414
can be
fully closed in order to both retain air within the airbag 402 and prevent the
airbag
402 from filling with water. As shown in Figure 14, alternative embodiments
can
include multiple vent valves 414 in series.
Turning next to Figure 16, an alternative embodiment is shown wherein the
vent passage 408 is at least partially contained within the fuselage 416 of
the
aircraft. While the bottom side of the vent passage 408 is shown flush with
the under
side of the fuselage 416, in alternative embodiments the vent passage 408 can
extend through other portions of the aircraft. In the illustrated embodiment,
the
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second opening 412 opens to the under side of the fuselage 416. In alternative
embodiments, the second opening can open to the top, side, or other part of
the
aircraft so long as the second opening will not be obstructed by the airbag
402.
The embodiment shown in Figure 16 also shows an example of an
embodiment of the venting system 400 having multiple vent valves 414. The
venting
system 400 as shown in Figure 16 includes a pop-off vent valve 414a in series
with
an active vent valve 414b. Still further embodiments can include any number of
vent
valves 414 as desired.
Turning next to Figures 17 and 18, more detailed views are shown of
examples of embodiments of active vent valves 414c and 414d, respectively,
that
can be used with the venting system 400 in combination with, or in place of,
the
active vent valve 120 described above in connection with vent 118. It should
be
appreciated that these are only examples, and that many modifications are
possible
to these embodiments, and that there are many other types of controllable
valves
can be used as an active vent valve 414.
Referring to Figure 17, vent valve 414c is an embodiment of an active vent
valve 414 that can be controlled to be fully opened (shown in phantom), fully
closed
(shown in solid lines), or partially opened to any of a continuous range of
partially-
opened positions between the fully open and fully closed positions for
regulating the
flow of air through the vent passage 408. In the view shown in Figure 17, air
travels
from the airbag 402 in the direction indicated by arrow 426. The vent valve
414c
includes a vent plate 430 that is hingedly connected to at least a portion of
the vent
passage 408. The vent plate 430 is configured to fully seal the vent passage
408
when in the closed position (shown in solid lines) such that air cannot flow
through
the vent passage 408 when the vent plate 430 is in the fully closed position.
An
actuator 432 is attached to the vent plate 430. The actuator 432 is configured
for
moving the vent plate 430 to any desired position, between and including the
closed
position (shown in solid lines) and fully open position (shown in broken
lines) as
directed by a control system such as control system 126 or controller 354 as
described above.
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In the embodiment shown in Figure 17, the vent passage 408 includes a
shoulder 434. The shoulder 434 helps provide for a better seal between the
vent
passage 408 and the vent plate 430. The shoulder 434 can also act as a stop,
preventing the vent plate 430 from hyperextending beyond the fully closed
position
towards the airbag 402, for example under the force of incoming water as might
otherwise occur if the airbag 402 were to deploy during a water landing or
crash. In
alternative embodiments, the shoulder 434 can extend up into the vent passage
408
rather than extending outwardly from the vent passage 408 as shown in Figure
17.
Referring next to Figure 18, the vent valve 414d includes many of the same
elements as vent valve 414c, and therefore retains many of the same element
numbers. The main difference between vent valve 414c and vent valve 414d is
that
vent valve 414d includes a controllable locking system 440. The locking system
440
includes an actuator 442 or the like that can be controlled to move between a
retracted position shown in solid lines and an extended position shown in
broken
lines. When the actuator 442 is in the retracted position, the vent plate 430
can be
moved by actuator 432 from the closed position to any desired partially or
fully
opened position. When the actuator 442 is in the extended position, the vent
plate
430 is locked into the fully closed position.
While this disclosure has referenced at least one illustrative embodiment,
this
description is not intended to be construed in a limiting sense. Various
modifications
and combinations of the illustrative embodiments, as well as other
embodiments, will
be apparent to persons skilled in the art upon reference to the description.
